The application of external tire pressure gauges has gotten wider and wider and their working principle is also well known. Presently, the major improvements made in relevant art upon the external tire pressure gauge focus on physical construction of the gauge. On one hand, it is desired that the product size is as small as possible and on the other hand, it is also desired that the mounting structure is stable and safety.
Reference is made to Chinese Patent Application No.: CN102310734-A published on Jan. 11, 2012 by Chinese Patent Office. It is disclosed in this application an external tire pressure sensing device including a base, a sensor, a circuit board used for integrated control circuit, a button battery, and a packing suite. A threaded hole is defined axially in the base for cooperating with a gas nozzle. In addition, a circular platform is formed on the top portion of the base. The device includes a sealable venting member having a supporting platform tightly engaged with the circular platform, a communication portion placed into the base screw hole from the bottom of the supporting platform to push out a gas outlet valve of the gas nozzle, and a communicating hole. The sensor is installed on the bottom surface of the circuit board so as to be electrically connected with a control circuit of the circuit board. A sensing portion located on a bottom surface of the sensor is engaged tightly with the communicating hole of the sealable venting member. The button battery is positioned on a top surface of the circuit board and electrically connected with the control circuit. An extension cylinder is provided on the bottom portion of the base; a plurality of radial screw holes is defined in a circumferential wall of the extension cylinder; and a corresponding number of screws passes through respective radial screw holes and then are locked with a circumferential wall of the gas nozzle.
In above patent application, on one hand, the internal construction of the tire pressure gauge becomes more compact by providing the sealable venting member, thereby reducing entire size of the gauge; on the other hand, the tire pressure gauge is firmly installed with the gas nozzle by tightly pressing against the circumferential wall of the gas nozzle using a screw which passes through the screw hole defined in the extension cylinder provided on the bottom portion of the base. Though this solution actually achieves its intended purpose, it is found by practice that the screw pressed forcibly against the gas nozzle has very small size and operation room between the hub and base is also limited, thus resulting in inconvenience in alignment of the screw with the screw hole and alignment of the cap portion of the screw with a screwdriver. Accordingly, manipulation of the screw is very difficult. Moreover, generally two or three screws are required to be disposed radially on the gas nozzle to generate stable and balanced mechanical construction. More screws should be operated by the user to mount or dismount the tire pressure gauges, thus resulting in inconvenience.
Furthermore, as the dimension of the tire pressure gauge gets smaller, manual assembling and disassembling of the packing suite and base gets much difficult. In addition, no design is disclosed in above disclosure for assisting in disassembling operation and accordingly, this solution is insufficient and is to be improved.